1. Field of the Invention
This invention relates to a process for producing tertiary butyl alcohol (TBA) in a higher yield than previously obtainable by reacting isoolefins, in particular isobutylene, with water and more particularly it is concerned with a process for producing TBA in a higher yield by reacting isobutylene with water in the presence of an oxy acid or its derivative using a solid catalyst, preferably, an acid-type cation exchange resin.
2. Description of the Prior Art
For the production of TBA by hydration of isobutylene, there have been proposed an indirect hydration method comprising absorbing isobutylene in sulfuric acid and hydrolyzing the formed sulfuric acid ester and a direct hydration method comprising using a solid acid or an acidic aqueous solution as a catalyst.
Of these methods, the method using an aqueous solution of sulfuric acid has the disadvantage that large amounts of by-products are formed through dimerization or trimerization of isobutylene and that there are problems of the corrosion of the apparatus and the treatment of the waste sulfuric acid. In most of the direct hydration methods using a solid acid or acidic aqueous solution as a catalyst, on the other hand, some activity appears only at a high temperature such as about 200.degree. C. or higher. Since the equilibrium of the hydration reaction is disadvantageous for the formation of the alcohol with the rise of temperature, it is necessary to conduct the reaction under a very high pressure in order to obtain a sufficient yield at such a high temperature. In this respect, a sulfonic acid-type ion exchange resin is a good catalyst capable of advancing the reaction at a relatively low temperature and low pressure. A number of methods using the same have been proposed.
For example, "Industrial and Engineering Chemistry" Vol. 53, No. 3, page 209-211 describes a method wherein isobutylene is continuously hydrated using an ion exchange resin as a catalyst, but this method is not always satisfactory because water and isobutylene form a heterogeneous system and thus give an insufficient reaction speed and yield. For the purpose of solving this problem, there have been proposed a method comprising reacting isobutylene or an isobutylene-containing hydrocarbon with an aqueous solution of an organic acid using an acidic ion exchange agent as a catalyst (Japanese Patent Application (OPI) No. 32116/1975 and Japanese Patent Publication No. 14044/1978); a method comprising carrying out the reaction with addition of a monohydric alcohol to the reaction system and using a similar catalyst (Japanese Patent Application (OPI) No. 137906/1975) and a method comprising carrying out the reaction with addition of glycol, glycol ether or glycol diether to the reaction system (Japanese Patent Application (OPI) No. 59802/1976 and U.S. Pat. No. 4,096,194).
In these methods for producing TBA by directly hydrating isobutylene, some improvement in reaction rate is found but, on the other hand, by-products are formed such as adducts of isobutylene with organic acids or organic solvents which are added to the reaction system. These by-products and organic solvents added to the reaction system make it difficult to separate and purify TBA by distillation utilizing the difference of their boiling points. In the case of using organic acids such as acetic acid, the apparatus tends to become corroded.